High concentrations of hydrogen peroxide can cause adverse effects on composition and structure of teeth. However, the addition of calcium and fluoride in bleaching agents may reduce enamel demineralization.Objective:To evaluate chemical changes of sound and demineralized enamels submitted to high concentrations of hydrogen peroxide containing fluoride (F) or calcium (Ca).Material and Methods:Enamel blocks of bovine incisors with standard dimensions were obtained and half of them were submitted to pH-cycling to promote initial enamel caries lesions. Sound and demineralized enamel samples were divided into (n=10): (C) Control (no whitening treatment); (HP) 35% hydrogen peroxide; and two experimental groups: (HPF) 35% HP+0.2% F and (HPC) 35% HP+0.2% Ca. Experimental groups were submitted to two in-office bleaching sessions and agents were applied 3 times for 15 min to each session. The control group was kept in remineralizing solution at 37°C during the bleaching treatment. The surface mineral content of sound and demineralized enamels was determined through Fourier Transform Raman spectroscopy (FT-Raman), Energy dispersive Micro X-ray fluorescence spectroscopy (μ-EDXRF); and the subsurface, through cross-sectional microhardness (CSMH). In addition, polarized light microscopy (PLM) images of enamel subsurface were observed.Results:According to three-way (FT-Raman and μ-EDXRF analyses) or two-way analysis of variance (ANOVA) (CSMH) and Tukey test (α=5%), the calcium or fluoride added to high-concentrated bleaching agents increased phosphate and carbonate concentrations on sound and demineralized enamels (p<0.05). However, HPC and HPF were unable to completely reverse the subsurface mineral loss promoted by bleaching on sound and demineralized enamels. The calcium/ phosphate (Ca/P) ratio of sound enamel decreased after HP treatment (p<0.001).Conclusion:Even though experimental bleaching agents with Ca or F reduced mineral loss for both sound and demineralized enamel surfaces, these agents were unable to reverse the enamel subsurface demineralization.

Colorimetric evaluation was performed using a spectrophotometer (ΔE, ΔL, Δa, Δb) and a visual shade guide (ΔSGU). Calcium (Ca)/phosphorous (P) ratio was quantified in the enamel microbiopsies. Measurements were performed at baseline (T 0), after bleaching (T B) and in the 14-day follow-up (T 14). At each bleaching session, a visual scale determined the absolute risk (AR) and intensity of tooth sensitivity (TS). Data were evaluated by one-way (ΔE, Δa, ΔL, Δb), two-way repeated measures ANOVA (Ca/P ratio), and Tukey post-hoc tests. ΔSGU and TS were evaluated by Kruskal-Wallis and Mann-Whitney, and AR by Chi-Squared tests (a=5%). Results: LED produced the lowest ΔE (p<0.05), but LED/HP promoted greater ΔE, ΔSGU and Δb (T 14) than HP (p<0.05). No differences were observed in ΔE and ΔSGU for LED/CP and HP groups (p>0.05). ΔL and Δa were not influenced by LED activation. After bleaching, LED/CP exhibited greater Δb than CP (p>0.05), but no differences were found between these groups at T 14 (p>0.05). LED treatment promoted the lowest risk of TS (16%), while HP promoted the highest (94.4%) (p<0.05). No statistical differences of risk of TS were found for CP (44%), LED/CP (61%) and LED/HP (88%) groups (p>0.05). No differences were found in enamel Ca/P ratio among treatments, regardless of evaluation times. Conclusions: Violet LED alone produced the lowest bleaching effect, but enhanced HP bleaching results. Patients treated with LED/CP reached the same efficacy of HP, with reduced risk and intensity of tooth sensitivity and none of the bleaching protocols adversely affected enamel mineral content.

Objective: The aim is to evaluate the effect of violet light (VL) and nonthermal atmospheric plasma (NTAP) combined with or without 35% hydrogen peroxide (HP) and 37% carbamide peroxide (CP).Methods: Bovine crowns were divided into (n = 10) VL, VL/HP, VL/CP, NTAP, NTAP/ HP, NTAP/CP, HP, CP, and C (control) groups. Color and whiteness change (CIELAB-ΔE ab, CIEDE2000-ΔE 00 , whiteness index-ΔWI D ), color parameters (ΔL, Δa, and Δb), and intrapulpal concentration (μL/mL) of HP were assessed by spectrophotometry.Scanning electron microscopy evaluated the morphology of enamel surface. Data were analyzed by two-way analysis of variance and Tukey (ΔE ab , ΔE 00 , ΔWI D , ΔL, and μL/mL) and Kruskal-Wallis and Mann-Whitney tests (Δa and Δb, α = 5%).Results: VL increased ΔE ab and ΔWI D of CP (P < .05). VL and NTAP alone resulted in perceptible color and whiteness change, but lower than those in the gel-treated groups (P < .05). Activation modes increased ΔL compared with that of C, but only VL enhanced Δb when applied alone or combined with CP. VL and NTAP did not increase HP diffusion (P > .05) or cause alterations in enamel morphology. However, HP and CP promoted topographical changes.Conclusion: VL and NTAP changed color to a lesser extent than bleaching gels. VL produced supplementary effectiveness only for CP (ΔE ab and ΔWI D ), without increasing HP diffusion or changing enamel morphology. Clinical Significance: Although violet LED light and nonthermal atmospheric plasma (NTAP) promoted in vitro perceptible bleaching without compromising enamel morphology, bleaching gels (hydrogen peroxide and carbamide peroxide) were more Part of this work was presented during poster session of the Annual Meeting

Introduction Sterilization methods adopted in Human Teeth Bank can promote structural changes in enamel and dentin. Thus, the ideal method should combine the antimicrobial efficacy and preservation of the substrate biomechanical properties. Aim Evaluated the morphology and physical properties of enamel and dentin of extracted human teeth, after being submitted to different sterilization methods. Method Sixteen extracted third molars were sectioned in the following tooth regions: mesio-distal, vestibular-lingual and at the cement enamel junction. Forty specimens were selected according to values of microhardness and roughness initials, and distributed in four experimental groups (n = 10/group): Group 1 = Autoclave 121 °C (30 minutes); Group 2 = 2.5% Sodium hypochlorite (07 days); Group 3 = 5.25% Sodium hypochlorite (07 days); Group 4= 30% Acetic Acid (7 days). After sterilization, the microhardness, roughness and morphology of enamel and dentin were evaluated. Data were analyzed by paired t-test, Wilcoxon, Kruskal-Wallis and Analysis of Variance. A significance level of 5% was adopted. Result All sterilization methods altered the microhardness and roughness of the dentine (p <0.05). Regarding to enamel, the microhardness was affected only by Autoclave and 2.5% Sodium hypochlorite treatment (p <0.05). A large aperture of the enamel pores and dentinal tubules was verified in the micrographs. Conclusion The sterilization methods adopted altered the morphology and/or physical properties of enamel and dentine.

Banco de dentes humanos (BDH) é uma entidade sem fins lucrativos que tem a finalidade de recepcionar, armazenar, catalogar e manter em boa conservação dentes humanos para pesquisa e treinamento laboratorial pré-clínico de estudantes.  No entanto, muitos cirurgiões-dentistas desconhecem a importância do BDH. O objetivo deste estudo foi avaliar o conhecimento dos cirurgiões-dentistas das Unidades Básicas de Saúde (UBS) do município de Teresina/PI sobre condutas diversas relacionadas aos BDHs. O presente estudo é do tipo observacional com amostragem probabilística estratificada com alocação proporcional, que utilizou entrevistas. Mais da metade dos cirurgiões-dentistas afirmaram ter conhecimento da existência de BDHs no Brasil, porém 81% desconheciam a existência do BDH da Universidade Federal do Piauí (UFPI). Todos os entrevistados foram a favor da doação e consideram o dente como um órgão, entretanto 95,2% nunca fez doação de dentes para um BDH. O lixo foi o destino mais comum após exodontias. Diante disto, foi possível concluir que não há doação de dentes humanos pelos cirurgiões-dentistas entrevistados, possivelmente, devido ao desconhecimento da existência do BDH da UFPI e suas peculiaridades.